POLYSTYRENE AEROSOLS - ELECTRICAL CHARGE AND RESIDUE SIZE DISTRIBUTION

The complete size distribution of polystyrene aerosols produced from a dilute hydrosol of the polystyrene latex particles by the atomization and evaporation process has been measured over the size range 0.002-5 μ in 18 size intervals by means of an aerosol counting and size-distribution measuring system consisting of three instruments in parallel operation: a General Electric condensation nuclei counter, an electric particle counter and a Royco optical particle counter. The concentration of the residue particles resulting from the evaporation of the empty liquid droplets containing no PSL particles has been found to be approximately five orders of magnitude higher than the monodisperse PSL particles. The use of an impactor with a sharp 2-μ droplet cut-off has been shown to be effective in improving the monodispersity of the generated polystyrene aerosol. The improvement apparently has resulted from the reduced number of multiplets formed. The electrostatic charge on the PSL particle has been measured and the median charge has been found to be on the order from 10 to 100 elementary electron units. However, some particles have been found to carry over 600 units of charge. Charges of these magnitudes are approaching or even exceeding the maximum charge that can be placed on these particles in an electrostatic precipitator and undoubtedly can have a very substantial effect on the behavior of the aerosol. A radioactive Kr-85 gas of 0.5 mc activity has been found to be an effective means of neutralizing the aerosol charge. © 1968.